Device for detecting the rotation speed of a rotating element

ABSTRACT

The invention relates to a device for detecting the rotation speed of a rotating element supported by at least one external rotating ring with at least one roller bearing. At least one internal non-rotating ring of the roller bearing is solidly connected to a shaft mounted on a support. The inventive device includes a non-rotating sensor adjacent to the roller bearing and a rotating encoder. The encoder is at least partially fixed by magnetization to a flange which is integral to the rotating ring and which is made from a magnetizable material.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to detection of the rotation speed of arotating element and can be used in roller skates, skateboards,bicycles, or scooters, in which a device for detection of wheel rotationis provided.

[0003] 2. Description of the Related Art

[0004] In general, wheels of in-line roller skates are mounted onebehind the other on the side plates of a support fixed to a shoe. Eachwheel is free to rotate about a fixed spindle through two rollerbearings with the ends of the said spindle fixed to the support plates.Skates with coaxial wheels and skateboards are also known.

[0005] Document FR-A-2 772 920 describes a device for detection of therotation speed of a wheel on an in-line skate where the wheel issupported by rotating rings of two roller bearings with the fixed ringsof the two roller bearings fixed to a spindle mounted on a support. Thedetection device includes a sensor and an encoder placed in a volumedelimited in the axial direction by two roller bearings and in theradial direction by the reaming in the wheel. This type of assembly isusually satisfactory. However, it is desirable to be able to easilyequip one of the wheels of a skate using a conversion kit where theconversion may be performed by a simple addition without any particularmachining or reworking of existing parts.

SUMMARY OF THE INVENTION

[0006] The invention is designed to facilitate mounting of asensor/encoder assembly in a roller bearing, particularly a rollerbearing of an in-line skate, skateboard, scooter, etc. The invention isadvantageously applicable to other applications to enable easy assemblyof an encoder on a rotating part.

[0007] The invention proposes a device for detection of the rotationspeed in which the elements comprising the sensor means and the encodermeans are substituted for the original elements or are installed on theoriginal elements without the need to make any modifications to therotating element or to the original parts remaining in the rotatingelement assembly.

[0008] According to one embodiment of the invention, the device fordetection of the rotation speed is designed to be used on a rotatingelement of the type supported by at least one external rotating ringwith at least one roller bearing, with at least one non-rotating innerring of the roller bearing fixed to a spindle installed on a support.The device includes a non-rotating sensor adjacent to the roller bearingand a rotating encoder. The encoder is at least partly fixed bymagnetization onto a side plate fixed to the rotating ring and is madefrom a magnetizable material. The encoder includes at least one magnetextending over part of the side plate at a fixed location in the radialand circumferential directions in the immediate vicinity of one face ofthe side plate facing the sensor such that the attraction force betweenthe magnet and the side plate participates in holding the said encoderin contact with the said side plate.

[0009] An adhesive means may also be arranged between the face of theside plate and the encoder.

[0010] The side plate may be a sealed side plate installed in an annulargroove of the rotating ring and extending close to the non-rotatingring.

[0011] In one embodiment of the invention, the rotating element issupported by rotating outer rings of two roller bearings. Non-rotatinginner rings of the two roller bearings are fixed to a spindle installedon a support. The detection device includes a sensor and an encoderarranged in a volume delimited in the axial direction by two rollerbearings and in the radial direction by a cylindrical surface coaxialwith the roller bearings and with a diameter equal to the outsidediameters of the outer rings of the roller bearings. The detectiondevice may easily be adapted to a standard in-line skate, on which therewas no previous detection means, simply by interchanging elements or byinstalling additional elements without requiring any modification to theoriginal parts of the skate. Therefore, it is very easy to use thedetection device.

[0012] In one embodiment, the magnet is in contact with the side plate.The magnet may be bonded onto the side plate. The magnet may be embeddedin an annular support. The annular support may be in contact with theside plate. The annular support may be bonded onto the side plate. Themagnet is a permanent magnet and is in the form of a disk or a wafermade by sintering of powder components. For example, samarium cobalt(SmCo) magnets could be used in order to make a compact magnet withstrong magnetic properties.

[0013] In one embodiment, the annular support is made of a flexiblematerial.

[0014] In one embodiment, the annular support is centered on the wheel.

[0015] In one embodiment, the outside diameter of the annular support isslightly greater than the reaming of the wheel.

[0016] The annular support may be centered on a portion of the sideplate.

[0017] In one embodiment, the encoder includes an active encoding partand a magnetization part formed from the same material.

[0018] In one embodiment, the encoder is formed from locally magnetizedplastoferrite.

[0019] Advantageously, the magnet is housed in a compartment. Thecompartment may be made by insert moulding of a flexible material on theoutside face of the side plate.

[0020] In one embodiment, the compartment has a parallelepiped shape.

[0021] The walls of the compartment may be approximately perpendicularto a radial plane. Preferably, the walls of the compartment include apart that flares outwards to form an entry chamfer, a central partacting essentially to retain the magnet, and a reverse tapered part nearthe bottom of the compartment.

[0022] In one embodiment, the device includes a sealing lip formed froma flexible material.

[0023] In one embodiment, the device includes a disk-shaped element madefrom the said flexible material with an approximately radial outsideface of the encoder. The magnet may be flush with the said face or itmay be set back from it.

[0024] In one embodiment, the disk-shaped element is fixed in a groovein the rotating ring.

[0025] In one embodiment, the disk-shaped element has an inside edgeforming a dynamic seal between the element and the contact surface ofthe non-rotating ring, either in friction or with a narrow gap.

[0026] In one embodiment, the magnet is held in place in the compartmentpartly by a magnetic force and partly by a mechanical force due toclamping in the said compartment.

[0027] According to one aspect of the invention, a rotation speeddetection device is intended for use with a rotating element of the typesupported by at least one rotating outer ring with at least one rollerbearing with at least one non-rotating inner ring of the roller bearingfixed to a spindle installed on a support. The device includes anon-rotating sensor adjacent to the bearing and a rotating encoder. Theencoder is fixed onto a side plate fixed to the rotating ring. Theencoder means includes a disk-shaped element provided with at least onecompartment and at least one magnet housed in the compartment.

[0028] According to one aspect of the invention, an encoder will be usedin a device for detection of the rotation speed of a wheel supported byat least one rotating outer ring with at least one roller bearing withat least one non-rotating inner ring of the roller bearing fixed to aspindle installed on a support where the device includes a non-rotatingsensor adjacent to the roller bearing. The encoder includes at least apartial magnetization method of attachment to a side plate made of amagnetizable material. The encoder includes at least one magnetextending over part of the side plate placed in the radial direction andin the circumferential direction and placed in the immediate vicinity ofone face of the side plate facing the sensor such that the attractionforce between the magnet and the side plate participates in retainingthe said encoder in contact with the said side plate.

[0029] The encoder may include one or several magnets.

[0030] According to one aspect of the invention, roller skates within-line wheels, a skateboard, a scooter, and a bicycle all have morethan one wheel. At least one wheel is supported by at least one rotatingouter ring with at least one roller bearing and at least onenon-rotating inner ring of the roller bearing fixed to a spindleinstalled on a support. The skate includes a device for detection of therotation speed of the wheel and includes a non-rotating sensor adjacentto the bearing and a rotating encoder. The encoder is fixed, at leastpartly by magnetization, on a side plate fixed to the rotating ring andis made of a magnetic material. The encoder includes at least one magnetplaced in the immediate vicinity of the face of the side plate facingthe sensor such that the attraction force between the magnet and theside plate participates in retaining the said encoder in contact withthe said side plate.

[0031] A battery or a rotating generator may be provided to power theemitter.

[0032] The sensor and the encoder may be placed without changing thestructure or original shape of the wheel.

[0033] Thus, the result is a skate for which the detection device isparticularly well protected against external pollution and shocks andfor which the wheels can be replaced while keeping the same detectiondevice that can also be fitted on a skate that did not have oneoriginally.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] This invention will be better understood after reading thedetailed description of some embodiments used as examples that are in noway limiting, and are shown on the attached drawings in which:

[0035]FIG. 1 is an axial sectional view of a wheel of an in-line skateequipped with a detection device according to the invention where thesensor block is shown as an external view in the top part of the figure;

[0036]FIG. 2 is an axial sectional view of the encoder of the wheel inFIG. 1;

[0037]FIG. 3 is an elevation view of the encoder in FIG. 1;

[0038]FIG. 4 is a detailed view of FIG. 1 illustrating assembly of theencoder;

[0039]FIG. 5 is an axial sectional view of a bearing according toanother embodiment of the invention;

[0040]FIG. 6 is an axial sectional view of a bearing according toanother embodiment of the invention;

[0041]FIG. 7 is an elevation view of an encoder means according toanother embodiment of the invention;

[0042]FIG. 8 is an axial sectional view of a bearing fitted with theencoder in FIG. 7;

[0043]FIG. 9 is an axial sectional view of the encoder in FIG. 7;

[0044]FIG. 10 is an axial sectional view of a bearing according toanother embodiment of the invention;

[0045]FIG. 11 is a partial front elevation view of the bearing encoderin FIG. 10;

[0046]FIG. 12 is an axial sectional view of a wheel of an in-line skateequipped with a detection device according to another embodiment of theinvention where the sensor block is shown as an external view in the toppart of the figure;

[0047]FIG. 13 is a detailed partial view of FIG. 12;

[0048]FIG. 14 is a half-axial sectional view of the encoder in FIG. 12when it is being assembled;

[0049]FIG. 15 is a partial front elevation view of the encoder in FIG.12; and

[0050]FIG. 16 is a perspective view of the encoder in FIG. 12 beforeassembly of the magnet.

DETAILED DESCRIPTION OF THE INVENTION

[0051] As can be seen in FIG. 1, wheel 1 of an in-line skate is providedwith a reaming 2 that is extended by shouldered cylindrical bearingsurfaces 3 and 4 at each end for assembly of roller bearings 5 and 6.The two assembly contact surfaces 3 and 4 are concentric with the axisof rotation of the wheel and their diameters, exactly the same, are morethan the reaming of wheel 1. Roller bearings 5 and 6 are identical andare provided with a rotating outer ring 7 having rolling track 8, anon-rotating inner ring 9 having rolling track 10, and a row of rollers11, (e.g., example balls), placed between rolling track 8 and rollingtrack 10 and kept at a spacing from each other in the circumferentialdirection by a cage 12.

[0052] Outer ring 7 of each roller bearing is installed, using outercylindrical surface 7 a, inside the corresponding cylindrical bearingsurface of assembly 3 or 4 of wheel 1. Wheel 1 is single piece with thereaming 2 and rolling surface 1 a forming part of the same part.

[0053] Inner rings 9 of roller bearings 5 and 6 are supported by asleeve-shaped spacer 13 provided with shouldered cylindrical bearingsurfaces 14 and 15 at each end for assembly of roller bearings 5 and 6.The spacer 13 is installed on a spindle 16 that projects from both sidesof spacer 13 and wheel 1. The portions of the spindle that project fromspacer 13 enter the reamings 17 formed in each flange 18 and 19 ofsupport 20. The spindle 16 is held in place on one side by a head 21 andon the other side by a screw 22 that is screwed to the end of spindle 16and that is provided with a wide head 23 with a diameter greater thanthe diameter of the reaming 17 of flange 19 of board 20, and that bearson a radial surface of flange 19 thus fixing spindle 16 in position.

[0054] Roller bearing 6 is provided with sealing elements on each sideof the row of rolling elements 11 in the form of side plates 24 and 25.Sealing side plate 24 is located on the outside while sealing side plate25 is located on the inside facing roller bearing 5. Roller bearing 5 isalso provided with seal packing in the form of outside side plate 26 andinside side plate 27.

[0055] Sealing side plates 24 to 27 are made from a sheet blankincluding a portion in which the corresponding outer ring is fixed in agroove, a radial portion extending inwards, and a short cylindricalportion placed close to an outer cylindrical surface of thecorresponding inner ring.

[0056] Spacer 13 is made from a synthetic material and is in the shapeof a general surface of revolution with thin portions corresponding tocylindrical bearing surfaces 14 and 15 and a thicker central portion 13b extending radially towards the outside close to the reaming 2 of wheel1 between roller bearings 5 and 6. The reaming 13 a of spacer 13 is incontact with the outer surface of spindle 16.

[0057] In the central portion 13 b that forms a sensor support block,there is a sensor 28, a transmitter 29, and a battery 30 connected byelectrical connections. Transmitter 29 and battery 30 are embedded inthe synthetic material of the central portion 13 b. Sensor 28 isinserted in the said synthetic material while remaining flush with anannular radial surface 13 c facing side plate 27 of roller bearing 5.

[0058] An annular-shaped encoder element 31 is fixed to the radialportion of sealing side plate 27 of roller bearing 5. Encoder element 31has an external cylindrical surface 32 in contact with the reaming 2 ofwheel 1, a radial surface 33 in contact with a corresponding frontsurface 7 b of outer ring 7, a radial surface 34 in contact with theradial portion of sealing side plate 27, and a radial surface 35 placedfacing sensor 28 with a small air gap from it.

[0059] Encoder element 31 includes two magnets 36 and 37 that are usedto fix it onto the radial portion of sealing side plate 27 made from aferromagnetic plate. Magnets 36 and 37 are embedded in the syntheticmaterial forming encoder element 31 and centered in the reaming 2 ofwheel 1 and bearing in contact with the metallic sealing side plate. Allthat is necessary to equip a standard wheel with a detection device isto place the encoder element, described above, adjacent to the sideplate of one of the bearings and to replace the spacer. If the encoderitself is of the magnetic type, a magneto-sensitive sensor such as aHall effect probe can be used. The active part of the encoder elementmay be made from a locally magnetized plastoferrite.

[0060] The assembly operation is particularly simple. The encoderelement is inserted in the reaming of the wheel and brought into contactwith the metallic side plate. Since encoder element 31 is centered withrespect to the reaming 2 of the wheel, the magnets are perfectlypositioned with respect to the side plate in the radial direction. Asthey come into contact with the side plate, magnets 36 and 37 willcreate a sufficiently high axial adhesion force to keep the said encoderelement in contact with the rotating part of the bearing while the sideplate remains fixed to the outer ring 7 with itself fixed to wheel 1.Obviously, the connection between the side plate and the encoder elementcould be reinforced using an adhesive placed on the radial surface 34 ofencoder element 31 and/or by providing a small diametric interferencebetween the outside cylindrical surface 32 of encoder element 31 and thereaming 2 of wheel 1 to reinforce the attachment by a slightly tightinsert fit.

[0061] Obviously, the encoder element may include a single magnet or itmay include more than two magnets. It would also be possible to placeunmagnetized devices with identical masses diametrically opposite themagnets to avoid the formation of out-of-balance masses.

[0062]FIG. 4 shows how encoder element 31 can be installed on wheel 1 onwhich roller bearing 5 has already been fitted. After removing the otherbearing, an axial movement brings the encoder element into place fromthe side opposite roller bearing 5. It is made to slide along thereaming 2 of wheel 1 until magnet 36 comes into contact with sealingside plate 27.

[0063] In the embodiment shown in FIG. 5, encoder element 31 is similarto the encoder element of the previous embodiment except that it isprovided with a cylindrical centering bearing surface 38 that cooperateswith the crimping lip of the side plate that projects from the groove inthe side plate support formed in outer ring 9. In this case, the outsidediameter of encoder element 31 is smaller than the outside diameter inthe previous embodiment and no longer comes into contact with thereaming 2 of wheel 1. On the other hand, as before, radial surface 34comes into contact with the radial portion of sealing side plate 27.

[0064] In the embodiment shown in FIG. 6, magnet 36 is bonded directlyonto metallic side plate 27 of roller bearing 5 before the rollerbearing is placed in wheel 1. The magnetization in combination with theadhesive capacity of the glue is sufficient to fix side plate 27 andmagnet 36 together. Magnet 36 also acts as the active part of theencoder element. In other words, the encoder element consists simply ofone or several magnets fixed onto side plate 27 by magnetization andgluing. The magnetic characteristics of the magnet provide a means ofattachment to the side plate and also a means of generating a signalthat the sensor is capable of detecting.

[0065] In the embodiment shown in FIGS. 7 to 9, encoder element 31 isformed from a thin flexible disk with an adhesive radial face 34 whichmay be pre-coated with an adhesive. Two magnets 36 and 37 are insertedin the flexible disk. Encoder element 31 is fixed by gluing andmagnetization onto the radial portion of sealing side plate 27.

[0066] In the embodiment shown in FIGS. 10 and 11, sealing side plate 26is replaced by an annular friction joint 39 including a flexible part40, for example made of an elastomer, projecting at one end into thegroove in outer ring 7, and at the other end, in this case the innerend, rubbing through a lip seal 41 on an outside cylindrical part ofinner ring 9, and an armature or metallic side plate 42, arranged on thesame side as rolling elements 11 and fixed to flexible part 40,providing it with the necessary stiffness.

[0067] Side plate 27 is replaced by an annular friction seal 43 close toseal 39, except that flexible part 40 has at least one axialprotuberance 44 arranged locally and hollowed out in the middle to formcompartment 45 open on the outside opposite the rolling elements withthe bottom formed by the armature or side plate 42 or by a thinelastomer film bonded to armature 42. Magnet 36 is placed in compartment45 and is held in place by magnetization with armature 42 that willadvantageously be made of a ferro-magnetic material, for example steelplate.

[0068] Protuberance 44 and compartment 45 are made by insert moulding ofa flexible material on the armature of seal 42 at the same time as theother parts of the seal. Compartment 45 extends locally, occupying adetermined annular sector of flexible part 40, at least in thecircumferential direction.

[0069] Advantageously, a small interference may be provided betweenmagnet 36 and the axial walls 45 a of compartment 45 in order to supportmagnet 36 or to reinforce the support.

[0070] As a variant, magnet 36 may also be glued. The position of magnet36 in the radial and circumferential directions is controlled bycompartment 44.

[0071] As a variant, it could be envisaged to make the disk from a rigidmaterial or from a magnetizable material, for example plastoferrite. Themagnet then forms an integral part of the material forming the diskbeing made from a part of the said locally magnetized material.

[0072] In all embodiments, the device is easy to install in a wheel of astandard in-line skate.

[0073] All that is necessary in the embodiments shown in FIGS. 1 to 4and FIGS. 7 to 9 is to purchase a conversion kit including the magnetholder encoder element and the spacer including a sensor and atransmitter. The next step is to place the encoder element in contactwith one of the roller bearings and the spacer between the two rollerbearings. The skate is ready to operate by transmitting a signalrepresenting the wheel rotation speed that can be collected and used ona receiver worn like a wristwatch.

[0074] In the embodiment shown in FIGS. 5, 6, 10, and 11, a kitincluding a roller bearing pre-equipped with one or more magnets may beprovided. All that has to be done then is to replace one of the rollerbearings and install the spacer including a sensor and a transmitter asdescribed above.

[0075] In one variant, a device for detection of the rotation speed of awheel supported by at least one rotating outer ring with at least oneroller bearing and at least one non-rotating inner ring having theroller bearing fixed with a spindle mounted on a support includes anon-rotating sensor adjacent to the bearing and a rotating encoder. Theencoder is fixed to a support fixed to the rotating ring. The encoderincludes at least one magnet extending over part of the support locatedin the radial and circumferential directions and arranged in theimmediate vicinity of a face of the support oriented towards the sensor.The magnet is tightly housed in a compartment of the support such thatthe clamping force participates in retaining the said encoder in contactwith the said side plate. The support may be provided with a method ofsealing.

[0076] This embodiment is shown in FIGS. 12 to 16, on which thereferences of elements similar to those in the previous figures havebeen kept unchanged. This embodiment is similar to the embodiment shownin FIGS. 10 and 11, except that the armature or metallic side plate 42arranged adjacent to rolling elements 11 has a plane principal part andan outer lip folded slightly towards the plane defined by the center ofthe rolling elements. Only flexible part 40 is in contact with outerring 7. Apart from a rim 46 located in the groove of outer ring 7,flexible part 40 includes a double lip seal 47 in rubbing contact with acylindrical bearing surface of inner ring 9 and a disk-shaped centralbody 48 mainly formed in a radial direction near the plane principalpart of the armature or side plate 42. In other words, the central body48 extends in the radial direction approximately between the reaming ofouter ring 7 and the cylindrical contact surface of inner ring 9.

[0077] Central body 48 includes plane outer surface 49, usuallyapproximately radial, on the side opposite rolling elements 11.Compartment 45 is formed in central body 48 but in this case is notprovided with a protuberance for this purpose. Compartment 45, in thiscase, goes as far as the armature or side plate 42, which facilitatesretaining by magnetization, although this is not essential.

[0078] Rectangular-shaped magnet 36 is placed in compartment 45 and isheld there by the walls of the compartment being clamped on the magnet.The said walls are usually perpendicular to a radial plane in theircentral part 45 a. In the free state, magnet 36 is slightly larger thancompartment 45 in the radial and/or circumferential direction whichmaintains sufficient clamping in the installed state to keep the magnetin place. At the entry to the compartment, the walls flare outwardstowards the outside of the seal to form an entry chamfer 45 bfacilitating insertion of magnet 36.

[0079] The walls of the compartment are also flared slightly outwardsfrom central part 45 a towards armature 42 to form a reverse taper 45 cenabling the seal to penetrate freely as far as the bottom of thecompartment without any risk of being hindered by the formation of arubber rim. If the armature or side plate 42 is made of a magneticmaterial, the magnetic attraction between the magnet and the armature orside plate 42 will also participate in holding the magnet in place.However, it would be possible to envisage the use of an armature or sideplate 42 made of a non-magnetic material and particularly a rigidsynthetic material.

[0080] Magnet 36 is flush with the plane outside surface 49 of centralbody 48. As a variant, the magnet may be set back slightly from theplane outside surface 49.

[0081] The device according to the invention has been illustrated by anapplication for a skate wheel, but obviously it is applicable to anyrotating device for which detection of the angular movement does notnecessitate very high precision and can be done on the basis of one orseveral pulses per revolution. Therefore, the invention is alsoapplicable to skateboard wheels, scooter wheels, or bicycle wheels, andobviously these examples are in no way limiting.

What is claimed is:
 1. Device for detecting the rotation speed of arotating element (1) supported by at least one rotating outer ring (7)of at least one roller bearing (5), at least one non-rotating inner ring(9) of the roller bearing being fixed to a spindle (16) installed on asupport (20), the device including a non-rotating sensor means (31)adjacent to the bearing and a rotating encoder means (30), the encodermeans being partially fixed by magnetisation to a side plate (27) fixedto the rotating ring, and made of magnetisable material, characterisedin that the encoder means includes at least one magnet (36) extendingover part of the side plate located in the radial and circumferentialdirections and arranged in the immediate vicinity of a face of the sideplate oriented towards the sensor means, such that the attraction forcebetween the magnet and the side plate participates in retaining the saidencoder means in contact with the said side plate.
 2. Device accordingto claim 1, characterised in that the magnet is in contact with the sideplate.
 3. Device according to claim 1 or 2, characterised in that themagnet is bonded to the side plate.
 4. Device as claimed in any ofclaims 1 to 3, characterised in that the magnet is embedded in anannular support.
 5. Device according to claim 4, characterised in thatthe annular support is in contact with the side plate.
 6. Deviceaccording to claim 4 or 5, characterised in that the annular support isbonded onto the side plate.
 7. Device as claimed in any of claims 4 to6, characterised in that the annular support is centred on the wheel. 8.Device as claimed in any of claims 4 to 6, characterised in that theannular support is centred on a portion of the side plate.
 9. Device asclaimed in any of claims 1 to 8, characterised in that the encoder meanscomprises an active encoding part and a magnetisation means formed fromthe same material.
 10. Device as claimed in any of claims 1 to 3,characterised in that the magnet is housed in a compartment.
 11. Deviceaccording to claim 10, characterised in that the compartment is made byinsert moulding of a flexible material on the outside face of the sideplate.
 12. Device according to claim 10 or 11, characterised in that thecompartment has a parallelepiped shape.
 13. Device as claimed in any ofclaims 10 to 12, characterised in that the walls of the compartment areapproximately perpendicular to a radial plane.
 14. Device as claimed inany of claims 10 to 13, characterised in that the walls of thecompartment comprise a part that flares outwards to form an entrychamfer (45 b), a central part (45 a) acting essentially to retain themagnet, and a reverse tapered part (45 c) near the bottom of thecompartment.
 15. Device as claimed in any of claims 1 to 14,characterised in that it comprises a sealing lip formed from a flexiblematerial.
 16. Device according to claims 11 to 15, characterised in thatit comprises a disk-shaped element made from the said flexible materialand with an approximately radial outside face of the encoder means. 17.Device according to claim 16, characterised in that the magnet is flushwith the said face or it is set back from it.
 18. Device according toclaim 16 or 17, characterised in that the disk-shaped element is fixedin a groove in the rotating ring.
 19. Device as claimed in any of claims16 to 18, characterised in that the disk-shaped element has an insideedge forming a dynamic seal between the element and the contact surfaceof the non-rotating ring, either in friction or with a narrow gap. 20.Device according to claims 10 to 19, characterised in that the magnet isheld in place in the compartment partly by a magnetic force and partlyby a mechanical force due to clamping in the said compartment. 21.Encoder intended for use on a device for detecting the rotation speed ofa wheel (1) supported by at least one rotating outer ring (7) of atleast one roller bearing (5), at least one non-rotating inner ring (9)of the roller bearing being fixed to a spindle (16) installed on asupport (20), the device including a non-rotating sensor means (31)adjacent to the bearing, and the encoder comprising means for partlyfixing it by magnetisation to a side plate (27) made of magnetisablematerial, characterised in that the encoder means includes at least onemagnet (36) extending over part of the side plate located in the radialand circumferential directions and arranged in the immediate vicinity ofa face of the side plate oriented towards the sensor means, such thatthe attraction force between the magnet and the side plate participatesin retaining the said encoder means in contact with the said side plate.22. Encoder according to claim 21, characterised in that it comprisesone or several magnets.
 23. Roller skates, skateboards, scooters andbicycles comprising a detection device as claimed in any of claims 1 to20.